Quickstart

Register tools on an official MCP Server, then mount it on FastAPI (or any ASGI app).

from typing import Any

import mcp.types as types
from fastapi import FastAPI
from mcp.server import Server
from mcp_asgi_http import mount_mcp

server = Server("demo")


@server.list_tools()
async def list_tools() -> list[types.Tool]:
    return [
        types.Tool(
            name="echo",
            description="Echo a message",
            inputSchema={
                "type": "object",
                "properties": {"message": {"type": "string"}},
                "required": ["message"],
            },
        )
    ]


@server.call_tool()
async def call_tool(name: str, arguments: dict[str, Any]) -> list[types.TextContent]:
    return [types.TextContent(type="text", text=str(arguments.get("message", "")))]


api = FastAPI(redirect_slashes=False)


@api.get("/health")
def health() -> dict[str, str]:
    return {"status": "ok"}


app = mount_mcp(api, server, auth=None)

Run with uvicorn:

uvicorn main:app --host 127.0.0.1 --port 8000

MCP endpoint: http://127.0.0.1:8000/mcp

Prefer mount_mcp over Starlette Mount under Mangum / Function URL. See Serverless.